Mokau coastal erosion

The Mokau spit is located at the mouth of the Mokau River. The present spit formed between 1500-2000 years ago and has been subject to periods of erosion and accretion as a result of various influences operating on the high wave energy West Coast.

Council’s aerial photographs show that river floods, storm waves and changes in the river channel and its orientation have significantly influenced the shoreline at Mokau spit.

The spit is the location of the Te Naunau Urupa and over 30 dwellings. It was first subdivided in 1954 by the Department of Lands and Survey, although several baches have been located on the spit since the 1940s. On granting the subdivision, the local Council at that time noted that the area was subject to erosion and sand drift. 

By 1962, new section owners were reporting that severe erosion was occurring on the spit. At the end of 1965, the Crown had paid full or partial compensation to a number of section owners, including re-vesting 11 sections. In 1974 an additional strip of land along the waterfront was also vested as reserve. Subsequent major erosion events occurred during the mid-1990s and between 2004-2010. During this period, private beachfront landowners constructed a rock wall as an interim measure to protect their properties.

In 2013, the structural integrity of Point Road was at risk of being undermined. WDC constructed temporary rock cladding on the road reserve to protect the embankment and to attempt to reduce the rate of erosion of the road-end of Beach Road and Point Road. The intention at that time was to secure physical access to the affected properties to allow for managed retreat if properties needed to be relocated.  

The above aerial photo taken in 2004 shows the front edge (red line) of the sections located on Point Road.

The above aerial photo taken in 2012 shows considerable erosion of the shoreline has taken place. The yellow circles show the locations where WDC has constructed temporary rock cladding to the embankments.

Adaptive Management Strategy

WDC’s position for some time had been to work for and promote a managed retreat approach for both infrastructure and the owners of the properties at risk.  In 2017, the Resource Management Act was amended and the management of significant risks from natural hazards was elevated to a matter of national importance. In December 2017, the Government issued guidance for local Councils on coastal hazards and climate change. You can read this document here.  

In line with this guidance, Council is now assessing whether an adaptive management strategy would be a more suitable and tailored option for the Mokau spit. Adaptive management requires a ‘dynamic adaptive pathways planning approach’ which is more flexible and is designed for situations like the Mokau spit where there is uncertainty about how future physical conditions might affect the coastal environment

Adaptive management is also more sensitive to the community and its aspirations, acknowledging that communities will have different coping capacities and sensitivities to increasing risk. To help Council make this assessment, we have engaged the Focus Resource Management Group.  Principal members Jim Dahm and Bronwen Gibberd are currently working on testing a range of responses and future scenarios in order to help the community reduce or avoid risk. To help manage uncertainty, Council might agree trigger or decision points with the community and make a plan to implement these in both the short and long term. You can read more about this process here.

Health and safety

The road end no longer provides a safe access point to the foreshore.  A sign-posted alternative public access to the beach is located between No.21 and 23 Point Road.

A timber fence has been erected to help secure the area and access stairs put in to provide a safer route to the beach, however the steps can be compromised by coastal erosion so WDC urges the public to check and use their own judgement before using these.

People who choose to ignore the signs and climb over any security fencing, are not only risking their health and safety but are also committing an offence in breach of Section 9.1.1 (a) and (b) of the WDC Land Transport Bylaw. A person convicted of an offence against the Bylaw is liable for a fine not exceeding $20,000.